Captive pen cap

Abstract

A cap for the point of a pen or pencil includes a cap element that is affixed to the writing end of, and captive on, the pen or pencil. The cap is rotatably and slideably moveable between a first extended position for covering and protecting the point, and alternately, a second, retracted position in which the cap element moves further onto the pen or pencil to expose the point for writing.

Having described the invention, what is claimed as new and secured by Letters Patent is: 
     
       1. A cap structure for the point of a pen, comprising: A. a cap element, said cap element including (i) a forward end opening formed therein, (ii) a rearward end opening formed therein, (iii) a plurality of helical internal slots, said slots describing no more than one turn about said cap element, said slots terminating rearwardly in rearward terminations at selected points forward of said rearward end opening of said cap element, and (iv) a rear lip disposed about the periphery of said cap element opposite said forward end opening,   B. means for mounting said cap element to said pen for rotatable and longitudinal movement from a first position covering said point to a second, retracted position exposing said point for writing, said mounting means including a plurlaity of radially protruding barbs affixed to said pen proximate to said cap element and engaging said slots in said cap element so that rotation of said cap element causes said protruding barbs to contact successive portions of said helical slots, causing said cap element to move longitudinally, to said first covering position covering said point when said cap element is rotated in one direction, and to said second, retracted position with said point protruding through said forward end opening when said cap element is rotated in the opposite direction, said barbs engaging said rearward terminations of said slots when said cap element is in said first covering position, the engagement of said barbs with said rearward terminations preventing removal of said cap element from said pen when said cap element is in said first covering position, said barbs being forwardly beveled for (i) permitting said cap element to be assembled over said barbs during assembly of said cap structure, and (ii) preventing inadvertent removal of said cap element when said cap element is in said first position, and   C. a peripheral seat element affixed to said pen proximate to said cap element, for seatingly engaging said rear lip of said cap element when said cap element is in said retracted position, said rear lip and said peripheral seat element being radially dimensioned for collectively forming a selected radial interference fit when said cap element is in said retracted position, thereby enabling a user to hold said pen, for writing, by grasping said cap element.